Process of dyeing.



UNITED STATES ATENT FICE'.

MYRTIL KAHN, OF ELBERFELD, GERMANY, 'ASSIGNOR TO FARBENFABRIKEN 'OF EIJBERFELD 00., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SPECIFICATIONformingpart of Letters Patent N 0. 725,847, dated April 21, 1903.

Application filed January 27, 1903. $erial No- 140,'720f specimens.)

To all whom it may concern.-

Be it known that I, MYRTIL KAHN, doctor of philosophy, chemist, residing at Elberfeld,

vented a new and useful Improvementin Processes of Dyeing and I do hereby declare the,

following to be an exact and clear description of my invention.

I have foundthat black shades of great fastness can be obtained on dyeing wool with certain azo dyestuffs derived from ortho-amidophenol derivatives and on treating the dyed goods with chromium compounds reacting as oxidizing agents, such as chromates, bichromates, or the like. By the action of these chromium compounds the original shades varying from red to blue are changed into deepblack shades, distinguished for their fastness to the potting process, which is a finishing process for woolen piece goods. In this process the goods are entered into boiling water and allowed to remain there until the water is cold. The goods thus assumo a high degree of gloss and softness, and,

according to the eifect desired, the potting may be repeated several times. They also resist milling and washing and possess great fastness against the action of light. The coloring-matters which I use for this purpose can be prepared by combining the diazo compounds of o-amidophenol derivatives having the following general formula:

OH (1) 2 C li,

X meaning S0 11; COOH or CH 'SO H; Y meaning a hydrogen atom which can be replaced by OH,; halogen; N0 or SO I-I, such as o-amidophenol sulfonic acids, amidooxybenzoic acids, or amidooxybenzyl sulfonic acids (containing the amido and the hydroxy group in ortho position) or derivatives thereofsuch as amidocresol sulfonic acids, the sulfonic acids of o-amidosalicylic acid, or the halogenated or nitrated derivatives of all these compounds, with 1: 5 dioxynaphthalene having the formula:

can proceed as follows: Place the wool in a bath containing three to six per cent. sulfuric acid, ten per cent. Glaubers salt, and

six per cent. of the dyestuff prepared by combination of diazotized ortho amidophenolparasulfonic acid with 1: 5 dioxynaphthalene, bring slowly to boil and boil for fortyfive minutes. The reddish-violet shade thus obtained is'changed into deep black by boiling the dyed Wool for one-half hour in a bath containing three to four per cent. bichromate of potash and three to six per cent. sulfuric acid. For the treatment with the abovementioned chromium compounds the 01d dyebath can also be used. In this case the further addition of sulfuric acid is not necessary.

The process proceeds in an analogous manner on using other of the above-cited dyestuffs or other chromium compounds reacting as oxidizing agents. Of course instead of sulfuric acid another suitable acid may be used, such as aceticacid or the like.

'Havin g now described my invention and in what manner the same is to be performed, what I claim as new, and desire to secure by Letters Patent, is

The herein-described process for producing on Wool fast-black shades, which process consists in first dyeing Wool from acid-bath with dyestuifs obtainable by combination of the diazo derivatives of o-amidophenol derivatives having the above-given general formula with 1: 5 dioxynaphthalene and then treating 5 the dyed goods with chromium compounds reacting as oxidizing agents, substantially as described.

In testimony whereof I have signed my name in the presence of two subscribing wit- MYRTIL KAHN.

Witnesses: OTTO KONIG,

'1. ,A. RITTERSI-IAUS. 

